As of December 2020, roughly 2,800 zero-emission buses were delivered or ordered in the US and by the end of 2021, Canada is projecting their population of zero-emission buses to reach 250 which is a 24% increase over 2019. This number will likely increase due to several reasons. First, cities are becoming more conscience of the impact their fleets have on the environment and could benefit the communities they serve with improved air quality and lower greenhouse gas emissions. Second, federal grants are providing the funding for transit operators to acquire new buses.  Finally, the total cost for battery electric buses and fuel cell electric buses has declined in the past decade because of increasing technology maturity and manufacturing scale.

Many public transit authorities have an interest in introducing or expanding their use of zero-emission electric buses. But the move to zero-emission electric buses does not come without its own set of challenges. Thermo King has set out to create an all-electric bus HVAC system that can meet those challenges head-on, and even raise the bar when it comes to electrification of the transit industry.


As transits transition to all-electric bus fleets, the need to reduce power consumption of the HVAC system becomes more apparent. Traditionally, the HVAC system is one of the largest electrical loads on a transit bus, requiring as much as 40% of the total available electrical energy. But it doesn’t have to be this way. All-electric HVAC systems can have the ability to lighten the load on the batteries. Thermo King has launched a Next Generation Electric HVAC system that utilizes a single horizontal variable speed compressor to provide up to 25% more capacity and efficiency than current Thermo King electric HVAC systems. The single variable speed compressor eliminates the need for a second compressor and allows for a wider frequency range of 25 Hz to 90 Hz. This means more power only when needed, saving energy.


Moving to a more efficient bus fleet does not have to mean more money spent. Thermo King’s Next Generation Electric HVAC system also offers easy integration with a Thermo King inverter. This option takes away any need to source and integrate a different inverter, which can be costly and difficult. The largest consumer of energy on a bus is the HVAC system. Rather than drawing on power from the bus, a heat pump enables an HVAC system to draw power from the atmosphere. The Next Generation Electric HVAC was also designed to incorporate a heat pump and in 2022, a Thermo King heat pump option will be available. The heat pump extracts heat energy from the outdoor air, utilizing that heat to warm the cabin of the bus. The size of the system and the ambient temperature will determine how much heat can be made available. This system with the heat pump option enables transits to provide heat during colder months while consuming less power, likely enhancing the range of an electric transit bus.



Transits do not want to sacrifice rider comfort for sustainability. On a traditional bus, the engine and the HVAC systems are significant sources of noise. With Thermo King’s Next Generation Electric HVAC system, transits will potentially improve energy efficiency and rider comfort. Thermo King’s system utilizes backwards-facing inclined blowers that include noise suppressors. This technology yields a significant reduction in noise from the HVAC system in the bus. So even without an engine in an all-electric bus, with Thermo King’s new Next Generation Electric HVAC system, transit passengers and drivers are experiencing a much quieter ride.  This system also has improved interior temperature control and increased cooling capacity. Passengers will likely experience a more consistent temperature throughout the bus cabin. Further, the system will likely meet any specifications. The new system can cool down a bus to 70° F within thirty minutes +/- 3° F and can likely meet even the most stringent pull-down requirements from transit authorities.  The Next Generation Electric HVAC system not only potentially increases the energy efficiency of a transit bus, but may also improve rider comfort.


Thermo King’s Next Generation Electric HVAC system will provide one of the most efficient and highest capacity all-electric units to meet the challenge of any transit’s desire to grow in the electric space. The Next Generation Electric HVAC system offering is also an integral step into the future for Thermo King and is part of the evolveTM portfolio. Thermo King, a brand of global climate innovator Trane Technologies (NYSE: TT), has announced that it will invest more than $100 million over the next three years to deliver a fully electric product in every segment of the cold chain by 2023. The company’s all-electric portfolio, branded evolveTM, includes all-electric HVAC offerings and will extend to electric refrigeration solutions for truck, trailer, rail, air, and marine transport in North America, Latin America and Europe, Middle East, and Africa (EMEA) regions. The evolve portfolio aligns with customers’ goals to transition to more sustainable solutions for their fleets, and will help advance Trane Technologies’ 2030 Sustainability Commitments.

Learn more about the  Next Generation Electric HVAC or other Thermo King all-electric products.

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